Atlantoaxial Instability Posted bythespinebookadminApril 4, 2022Posted inTopics, Trauma Background Degen Downs RA Os odonteium Morquio Traumatic Atlas TL injury Radiographs ADI – <3mm adults <5mm children PADI (SAC) – = or > 14mm (<14 is an issue) LM displacement (sum of overhang) – 8.1mm